Fast-acting fastener driving tools are commonplace in the building industry. A plurality of fasteners, such as nails, screws or staples, are assembled in strip assemblies that are adapted for use in the magazine of such tools. It has been the general practice to provide such strip assemblies in a generally flat construction, in which fasteners are aligned generally parallel to one another, and are maintained in position by being bonded to a substrate. An example of one such structure is depicted in U.S. Pat. No. 5,733,085, incorporated herein by reference.
A successful fastener assembly, such as a nail strip, will depend upon various factors. Among them are the ease of use, the cost of manufacture, and reliability. By way of illustration, for a number of nailing applications, it has been regarded as important for a nail strip to be durable while being transported to and handled on the worksite, such that the strip of nails is intact when the carpenter is ready to use them, and preferably such that the nails are generally in proper alignment. It also has been regarded as desirable for the nail strip to be easily loaded into a magazine of the nail gun, with minimal force and without buckling (referred to in the art as “corrugation”) or other damage to the strip.
For helping to achieve a successful fastening operation, particularly using a power driving tool, the ability to manage (particularly on a consistent and reproducible basis) the energy needed to drive the fastener also has been regarded as important. In addition to the necessary energy to pass the nail into or through a workpiece, there is a component of energy needed for simply detaching the fastener from the nail strip. Of course, since many of these power driving tools are handled by human workers, weight and ergonomic considerations abound as well.
Another consideration for fastener assemblies is that because an adhesive is commonly employed, upon driving a fastener, a certain amount of the adhesive will tend to be subjected to the force of the driver. It is common that the adhesive will largely remain attached to the fastener and be driven into the workpiece. It is possible, however, that fragments of the adhesive will become detached, with the potential for scattering of the loose fragments about a work site. Another phenomena is known as “flagging”, and involves the tendency of pieces of adhesive to separate from fasteners during driving, and becoming lodged in the workpiece, but protruding outwardly from the insertion point, causing the workpiece under construction to have a potentially less pleasing appearance.
Practical requirements also impose design constraints upon fastener assemblies. For example, experience has shown a preference for any structures for carrying fasteners to have an adhesive layer thickness less than about 100 μm. Transport and handling considerations have favored relatively light weight materials. Of course, as gleaned from the above, these must be considered in light of the mechanical properties desired of the materials, such as appropriate tear resistance, stiffness or otherwise.
As can be seen, for the successful manufacture and use of a fastener assembly, such as a nail strip, there are a surprisingly large amount of potentially competitive design considerations. The mere selection of any adhesive to satisfy each of the above needs is extremely difficult, let alone the optimization of the properties of any such adhesive for the specific intended use. It would therefore be valuable to have an improved structure by which at least some, if not all of, the above needs can be met.
Other publications of potential interest to the teachings herein are U.S. Pat. No. 7,198,446 and Published U.S. Application No. 2003/0087996 (both incorporated by reference).